1. Field of the Invention
The invention relates to a wheelchair, more particularly to a wheelchair which generates little noise when operated.
2. Description of the Related Art
Referring to FIG. 1, a conventional wheelchair is shown to include a seat portion (B) and a pair of wheels (C) which are attached to two ends of a shaft (D). The shaft (D) is provided rotatably under the seat portion (B) such that the two ends thereof extend respectively from two sides of the latter. The shaft (D) is driven rotatably by a motor (A) which is mounted under the seat portion (B).
Although, the conventional wheelchair is capable of assisting a disabled person, it has a few drawbacks. For example, the wheelchair cannot be folded, and therefore, cannot be transported conveniently.
Referring to FIGS. 2 and 3, another conventional foldable wheelchair is shown to include a seat portion 30, a pair of stationary mounting plates 20 provided respectively on two sides of the seat portion 30, and a pair of wheels 10. Each of the stationary mounting plates 20 has a stationary shaft 251 extending centrally therefrom, a driving unit 21 and a gear unit 22 mounted thereon. The driving unit 21 is driven by a rechargeable battery unit 23 that is also mounted on the stationary plate 20. Each of the wheels 10 includes a rim 11, a central circular plate 24 and a plurality of spokes 13 which extend radially from the circular plate 24 to connect with the rim 11. The circular plate 24 has a central through-hole, a neck flange 15 that extends from the periphery of the through-hole and an annular toothed portion 12. The neck flange 15 of the wheel 10 is sleeved rotatably on the stationary shaft 251 of the stationary plate 20. During assembly, the annular toothed portion 12 of the circular plate 24 of the wheel 10 is meshed with a toothed wheel 223 of the gear unit 22 so that rotation of the driving unit 21 is transmitted to the wheel 10.
Since the conventional wheelchair shown in FIG. 2 is foldable, the conventional wheelchair can be conveniently stored and transported.
A main drawback of the conventional foldable wheelchair is that it generates a relatively loud noise due to engagement of the toothed circular plate 24 and the toothed wheel 223 of the gear means 22, thereby disturbing persons nearby.
A second drawback of the conventional foldable wheelchair is that the wheel cannot be disconnected from the gear unit. Thus, the user has to exert a considerable force in order to move the conventional wheelchair whenever manual operation is desired.